Almost 400 incidents of cyber harassment and bullying were investigated by police in Wales last year, we can reveal.

Victims of abusive, threatening or harassing messages sent via social networks included teenagers as young as 14.

The problem has increasingly hit the headlines in recent months with celebrity victims Katherine Jenkins and former Miss Wales Imogen Thomas complaining publicly about being subjected to vitriolic online attacks.

Away from such high profile cases, in the South Wales Police force area alone 331 harassment-related incidents classed as “e-crime” were investigated, but resulted in just three arrests.

A Freedom of Information request identified 46 cyber crimes in the Dyfed-Powys Police area, resulting in 12 arrests. Offences included 10 hate crimes, one kidnapping and one threat to kill. Eight victims were under the age of 20. In North Wales, where 18 crimes on social networks were recorded, police investigated one offender for harassment while using a false identity.

Two cases were referred to the High Tech Crime Unit in Gwent, involving harassment messages, and e-mails sent to trustees of an organisation alleging homophobic harassment and bullying. However no further action was taken.

The Child Exploitation and Online Protection (Ceop) Centre is currently running a programme called Thinkuknow to educate children and young people about the dangers of “trolling” they face online.

A spokesman said: “Trolling is a description given to someone’s online actions that are deliberately inflammatory or abusive. It ranges from posting a nasty comment on a social networking profile, or a football forum to extreme and persistent abuse.

“It could include harassment, bullying or anything that causes distress to another. The effects can be devastating. Too few people realise that in acting this way online you can quickly break the law. People may think they can remain anonymous when they are online, that they can say and do things they wouldn’t dream of doing in real life without consequences.”

A spokesman for eCrime Wales said: “The e-Crime Partnership, which includes the four Welsh police forces, works to raise awareness of e-crimes of all kinds. The fact that these incidents are now being reported by the public reflects the fact that people in Wales are becoming more aware of the issue generally and of the importance of passing details of such attacks to the police.”

Jonathan Bishop, a South Wales-based internet expert who recently ran a Trolling Academy tutorial, said that as the numbers of arrests were low, fixed penalties and Asbos should be used against cyberbullies for less severe offences. It would be more appropriate then if local authorities, particularly where vulnerable persons are affected, used their powers under New Labour’s anti-social behaviour legislation to issue fixed-penalties to those who harass others, he said. “Local authorities also have the powers to apply for Asbos against persons, which could tell the cyberbullies that they can go to jail for up to two years if they continue their abuse.”

Criminal cases involving the malicious use of false identities on social networks are becoming increasingly common.

In August James Edward Dunn, 28, from Middlesbrough, was jailed for seven years for raping a 15-year-old girl he had lured into meeting by lying about his age on Facebook.

At the time the investigating officer, Detective Constable Jolene Morrison, had urged teenagers who use Facebook to “only speak to people that they know” and to be aware that the person they think they are talking to may not actually be that person.

In September Sean Duffy, 25, from Reading, was jailed for 18 weeks for taunting the families of four dead teenagers on online tribute sites.

And in November, police in Mid Wales vowed to crack down on “trolls” after a 14-year-old sex abuse victim was subjected to an online smear campaign after her attackers were brought to justice.

Mr Bishop, a town councillor for Treforest, said the use of false identities – by “Snerts” who post messages to harm others, and “E-Vengers” who are driven to harm others they feel have wronged them – is a serious problem.